1. Field of the Invention:
The present invention relates generally to towing vehicles, and more particularly, to such vehicles equipped with a turntable mounted boom assembly having a telescoping boom and operated by three electrical motors independent of the vehicle drive train.
2. Description of the Prior Art:
In general, most towing vehicle designs in the past have included boom assemblies which are fixedly attached to the vehicle frame. Hydraulic or direct mechanical take-off assemblies are provided for utilizing power generated by the vehicle engine to drive the towing cable winches and other accessories. While such prior art devices have been found to be useful, they have not proven to be entirely satisfactory under all conditions of use since the rigid mounting of the boom assembly on the vehicle frame often requires that the entire vehicle be moved into awkward or dangerous positions in order to, for example, pull a car from a ditch alongside a main highway. In addition, by taking power directly from the vehicle drive train, special transmissions and other equipment are needed causing additional complexity and limiting the engine and transmission options which may be offered to potential purchasers of new towing vehicles.
Many prior art towing vehicles also provide a single set of controls directly mounted to the left or right rear quarter of the vehicle frame. Such direct interconnection is required for practical use of direct mechanical or hydraulic systems, and in many instances is quite convenient, such as when a vehicle is being linked to the towing vehicle for towing purposes. On the other hand, many instances occur where the direct and rigid attachment of winch controls on the vehicle serves as a material disadvantage. In general, whenever the towing cable is to be attached to a vehicle or other object located a fair distance from the towing vehicle, two operators are necessary. One to operate the controls, and the other to attach the cable and supervise progress of the vehicle or object being towed or hoisted. In these circumstances, the manpower required to accomplish a particular task is twice what otherwise would be necessary, and if the needed second operator is not available, considerable delays and inconvenience may result. A further disadvantage in those circumstances requiring two-man operation, is the fact that each man's safety requires full communication between both operators during the hoisting operation. If a heavy vehicle or unusually bulky object is being hoisted, and communications between the two operators are difficult, as for example during a severe storm during the night, it may be difficult for them to fully understand each other causing an extremely unsafe situation.
While the prior art is generally cognizant of the foregoing problems, solutions proposed heretofore have not provided a totally satisfactory and universally usable system. For example, U.S. Pat. No. 2,700,481 discloses a wrecking vehicle in which the hoisting cable can be electrically controlled; however, the system fails to provide for the remote, electrical control of a boom turntable, and the electrical remote control of a telescoping boom. U.S. Pat. No. 2,637,447 is illustrative of another prior art towing vehicle exemplary of such systems wherein power to drive the boom assembly is taken from the vehicle drive train rather than being an independent system.
U.S. Pat. No. 2,559,733 shows a load hoisting device in which the hoisting cable is run along the underside of the boom and the boom is rotatable by means of a hydraulically moved cable slung around a large pulley. Again, this patent fails to provide for the independent, electrical, remote control of boom rotation, telescopic extension or retraction, and cable winch operation and requires the direct control of an operator for all uses.
U.S. Pat. No. 3,638,804 discloses an extendable and retractable boom on a hoisting apparatus, and different types of rotatable boom assembly cranes are shown in U.S. Pat. Nos. 349,582, 837,510, 2,071,905, 2,197,406, 2,557,484, 2,655,269, 3,093,248, 3,285,445, and 3,543,945.
A number of patents also illustrate towing or wrecking vehicles in which a towing cable is run down or along the underside of the boom assembly rather than being passed over the top of the boom assembly. Exemplary of such patents are U.S. Pat. Nos. 1,657,674, 3,158,266, 3,322,396 and 3,335,880.
U.S. Pat. No. 2,730,245 discloses an electronic control system in a hoisting apparatus, and U.S. Pat. No. 3,699,578 illustrates the remote control of a hoisting apparatus by means of a radio transmitter and receiver. Again, these patents fail to disclose a fully integrated, electronically operated hoist system for a towing vehicle having a rotating and telescoping boom fully operable by direct or remote control.